Known conventional metal bearings having a metal or alloy sintered compact as the main component thereof include oil-retaining bearings in which a lubricating oil is impregnated into a sintered compact (see Patent Document 1, for example). This type of metal bearing has self-lubricating properties, and the lubricating oil impregnated into the sintered compact can be made to exude onto the bearing surface by the exothermic heating or other effects that occur when the shaft member slides against the bearing surface.
Other metal bearings that have been proposed include a graphite-dispersion-type Cu-based sintered alloy bearing in which a copper-phosphorus alloy and graphite particles are mixed with copper-nickel-based alloy powder in a ball mill or the like, press-molded, and sintered (see Patent Document 2, for example). In such a metal bearing, excellent abrasion resistance can be demonstrated by the copper-nickel-based alloy having high strength and excellent corrosion resistance, as well as by the rigid copper-phosphorous alloy and the loose graphite having high lubricity.
Patent Document 1: Japanese Patent Application “Kokai” No. 2002-39183 (Prior Art)
Patent Document 2: Japanese Patent Application “Kokai” No. 2002-180162 (pp. 3 and 4)